Vibrations transmitted from an engine and a vehicle body may vibrate vehicle seats, which is uncomfortable to passengers. In the prior art, vehicle seats have been proposed to dampen vibrations. PTL 1 describes an example of such a vehicle seat that includes a weight made of lead or the like and arranged in a cushion material of the seat. The weight functions as a mass of a dynamic damper.
FIG. 22 shows a cross-section of a seat back (backrest) of the vehicle seat described in PTL 1. The vehicle seat includes a seat back frame 50, which functions as a frame member of the seat back, a cushion material 51, which encloses the seat back frame 50, and a cover 52, which covers the cushion material 51. The cushion material 51 is made of a foamed material such as a polyurethane foam. The cover 52 is formed from fabric, plastic, or synthetic leather.
A weight 53 is arranged behind the seat back frame 50 in the cushion material 51. The weight 53 is a metal plate made of lead, for example. The weight 53 is formed integrally with the cushion material 51 through insert molding. To increase the compatibility with the cushion material 51, the weight 53 is covered with a solid urethane foam 54.
In such a vehicle seat, the weight 53 functions as the mass of the dynamic damper and the cushion material 51 functions as the spring of the dynamic damper so that a vibration damping effect acts on the entire seat. Further, PTL 2 describes a headrest incorporating a weight that functions as a mass of a dynamic damper.